Question

The number of non-surjective mappings that can be defined from $A=\{1,4,9,16\}$ to$B=\{2,8,16,32,64\}$ is

• A. $1024$
• B. $20$
• C. $505$
• D. $625$

Answer 1

Answer: (D)

$625$

Here $n\left(B\right)>n\left(A\right)$, no function can be a surjective.

No of functions $=$ No of non-surjectives

Any elements of $A$ can be mapped to any of $5$ elements in $B$
So non surjective mapping from $A$ to $B$
$=5\times 5\times 5\times 5$
$=625$